US5493220A — Magneto-optic Kerr effect stress sensing system

Claim 1

Independent Claim 179 words

A magneto-optic Kerr effect stress sensing system comprising: a light source; a magneto-optic Kerr effect stress sensor; a polarizer disposed between said light source and said magnetooptic Kerr effect stress sensor wherein said light source directs a light beam toward said polarizer and said polarizer passes light having a first predetermined polarization said such that the light having the first predetermined polarization is incident upon said magneto-optic Kerr effect stress sensor; a polarization splitter disposed to intercept light specularly reflected from said stress sensor wherein said polarization splitter passes at least a portion of the light incident thereon and reflects at least a portion of the light incident thereon wherein said polarization splitter is oriented to mix in a predetermined manner portions of the light signal having the first polarization with portions of the light signal having a second different polarization; a first detector disposed to receive the portion of the light signal which passes through said polarization splitter; and a second detector disposed to receive the portion of the light signal which is reflected by said polarization splitter.

Claim 2

Dependent Claim 179 words

A magneto-optic Kerr effect stress sensing system comprising: a light source; a magneto-optic Kerr effect stress sensor; a polarizer disposed between said light source and said magnetooptic Kerr effect stress sensor wherein said light source directs a light beam toward said polarizer and said polarizer passes light having a first predetermined polarization said such that the light having the first predetermined polarization is incident upon said magneto-optic Kerr effect stress sensor; a polarization splitter disposed to intercept light specularly reflected from said stress sensor wherein said polarization splitter passes at least a portion of the light incident thereon and reflects at least a portion of the light incident thereon wherein said polarization splitter is oriented to mix in a predetermined manner portions of the light signal having the first polarization with portions of the light signal having a second different polarization; a first detector disposed to receive the portion of the light signal which passes through said polarization splitter; and a second detector disposed to receive the portion of the light signal which is reflected by said polarization splitter.

Claim 3

Dependent Claim 32 words

The sensing system of claim 1 wherein said magneto-optic Kerr effect stress sensor includes a plurality of layers wherein at least one of said plurality of layers is a magnetic thin film.

Claim 4

Dependent Claim 19 words

The sensing system of claim 1 further comprising a magnetic shield disposed about said magneto-optic Kerr effect stress sensor.

Claim 5

Dependent Claim 44 words

The sensing system of claim 1 wherein said magneto-optic Kerr effect stress sensor includes at least one magnetic layer having an in-plane uniaxial magnetic anisotropy and at least one magnetic domain having a magnetization that rotates coherently in response to an externally applied stress.

Claim 6

Dependent Claim 39 words

The sensing system of claim 4 wherein said at least one magnetic layer of said magneto-optic Kerr effect field sensor is provided from a magnetic thin film having at least one of: a ferri-magnetic layer; and a ferro-magnetic layer.

Claim 7

Dependent Claim 25 words

The sensing system of claim 5 wherein said magneto-optic Kerr effect stress sensor further comprises a dielectric layer over which said thin film is disposed.

Claim 8

Dependent Claim 34 words

The sensing system of claim 6 wherein said magneto-optic Kerr effect field sensor includes at least one magnetic layer having a saturation magnetostriction constant in the range of 25×10 -6 to 60×10 -6 .

Claim 9

Dependent Claim 25 words

The sensing system of claim 4 wherein: said magnetic thin film is provided having a thickness in the range of 5 nanometers to 500 nanometers.

Claim 10

Dependent Claim 24 words

The sensing system of claim 5 wherein at least one of the magnetic layers of said thin film is comprised of iron and boron.

Claim 11

Dependent Claim 139 words

A stress sensing system comprising: a light source; a magneto-optic Kerr effect stress sensor wherein said magnetooptic Kerr effect stress sensor comprises a magnetic film having first and second opposing surfaces and having a uniaxial anisotropy field characteristic of a predetermined intensity, wherein the magnetic film has at least one domain having a magnetization characteristic which rotates in response to application of an applied stress; a polarizer disposed between said light source and said magnetooptic Kerr effect stress sensor wherein said light source directs a light beam toward said polarizer and said polarizer passes light having a first predetermined polarization said such that the light having the predetermined polarization is incident upon said magnetooptic Kerr effect stress sensor; and a first detector disposed to receive the portion of the light signal reflected from said magneto-optic Kerr effect stress sensor.

Claim 12

Dependent Claim 139 words

A stress sensing system comprising: a light source; a magneto-optic Kerr effect stress sensor wherein said magnetooptic Kerr effect stress sensor comprises a magnetic film having first and second opposing surfaces and having a uniaxial anisotropy field characteristic of a predetermined intensity, wherein the magnetic film has at least one domain having a magnetization characteristic which rotates in response to application of an applied stress; a polarizer disposed between said light source and said magnetooptic Kerr effect stress sensor wherein said light source directs a light beam toward said polarizer and said polarizer passes light having a first predetermined polarization said such that the light having the predetermined polarization is incident upon said magnetooptic Kerr effect stress sensor; and a first detector disposed to receive the portion of the light signal reflected from said magneto-optic Kerr effect stress sensor.

Claim 13

Dependent Claim 49 words

The stress sensing system of claim 10 wherein: said magnetic film is provided having a thickness typically in the range of 5 nanometers to 500 nanometers and is provided from a first one of: a single layer of a ferro-magnetic material; and a single layer of a ferri-magnetic material.

Claim 14

Dependent Claim 16 words

The sensor system of claim 11 wherein said single layer is comprised of iron and boron.

Claim 15

Dependent Claim 65 words

The stress sensing system of claim 10 wherein said stress sensor is disposed such that a hard axis of said magnetic film is disposed at an angle 45 degrees relative to a light plane of incidence and such that a magnetization orientation for no applied stress lies transverse to the hard axis and at a 45 degree angle relative to the light plane of incidence.

Claim 16

Dependent Claim 98 words

The stress sensing system of claim 13 further comprising a polarization splitter disposed to intercept light specularly reflected from said stress sensor wherein said polarization splitter passes at least a portion of the light incident thereon and reflects at least a portion of the light incident thereon wherein said polarization splitter is oriented to mix in a predetermined manner portions of the light signal having the first polarization with portions of the light signal having a second different polarization and wherein portions of the lights signal which pass through said polarization splitter are detected by said first detector.

Claim 17

Dependent Claim 28 words

The stress sensing system of claim 14 further comprising a second detector disposed to receive the portion of the light signal which is reflected by said polarization splitter.

Claim 18

Dependent Claim 55 words

The stress sensing system of claim 13 further comprising a second polarizer disposed to intercept at least a portion of the light signal reflected from said stress sensor wherein said second polarizer attenuates the intensity of light having the first polarization wherein said detector is disposed to detect light which passes through said second polarizer.

Claim 19

Dependent Claim 20 words

The stress sensing system of claim 13 further comprising a magnetic shield disposed about said magneto-optic Kerr effect stress sensor.

Claim 20

Dependent Claim 30 words

The stress sensing system of claim 13 wherein said magneto-optic Kerr effect stress sensor includes at least one magnetic layer having a saturation magnetostriction constant greater than 25×10 -6 .

Claim 21

Dependent Claim 20 words

The stress sensing system of claim 10 wherein said magneto-optic Kerr effect stress sensor is disposed on a coupler half-block.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-02-19	1999-08-21	2000-02-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-02-19	2003-08-21	2004-02-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-02-19	2007-08-21	2008-02-20	$7700.00	Window Closed / Lapsed

Magneto-optic Kerr effect stress sensing system

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